Measure levels of endogenous and radioactively labeled tyrosine, tyramine, Dopamine, and Norepinephrine at intervals (0-72 hours) post-occlusion of the middle cerebral artery of primate Maccaca mulatta. The dynamic and regional properties of the experimental method allows the correlation of the above data with known morphological sequences of events of ischemia leading to neuronal cell death. Chronic studies (1-6 weeks) of similar lesions in a second group of primates will involve the injection of substances which allows the study of the permeability of proliferating capillaries at the boundaries of the infarcted areas by light and electron microscopy. The changes in capillary permeability may be instrumental in reducing infarction-associated cerebral edema.